Studying the highly bent spectra of FR II-type radio galaxies with the KDA EXT model

Abstract

Context. The Kaiser, Dennett-Thorpe & Alexander (KDA) (1997) EXT model, that is, the extension of the KDA model of FR(Faranoff & Riley)II−type source evolution, is applied and confronted with the observational data for selected FR II−type radio sources with significantly aged radio spectra. Aims. A sample of FR II−type radio galaxies with radio spectra strongly bent at their highest frequencies is used for testing the usefulness of the KDA EXT model. Methods. The dynamical evolution of FR II−type sources predicted with the KDA EXT model is briefly presented and discussed. The results are then compared to the ones obtained with the classical KDA approach, assuming the source's continuous injection and self-similarity. Results. The results and corresponding diagrams obtained for the eight sample sources indicate that the KDA EXT model predicts the observed radio spectra significantly better than the best spectral fit provided by the original KDA model.

The use of the Monte Carlo methods in studying Fanaroff‐Riley II‐type radio sources

“…This χ 2 value, although formally higher, is in fact slightly better for the actual model fit due to the fact that in this new research, the general (not reduced χ 2 , formerly giving the slightly lowered values, as in Kuligowska ) χ 2 test ranks were calculated (cf. also Kuligowska ()). Moreover, in the case of 3C 184, both the KDA model fits (derived with DYNAGE and Monte Carlo methods) clearly reproduce observational data for this source with less accuracy than the also‐published KDA EXT fit (Kuligowska (), section 4.3.1).…”